Re: Coverity: zram_recompress(): OVERRUN

[Sergey Senozhatsky]

On (22/11/10 19:15), Kees Cook wrote:
> On Fri, Nov 11, 2022 at 09:26:31AM +0900, Sergey Senozhatsky wrote:
> > On (22/11/10 08:47), coverity-bot wrote:
> > > *** CID 1527270:    (OVERRUN)
> > > drivers/block/zram/zram_drv.c:1727 in zram_recompress()
> > > 1721     		zstrm = zcomp_stream_get(zram->comps[prio]);
> > > 1722     		src = kmap_atomic(page);
> > > 1723     		ret = zcomp_compress(zstrm, src, &comp_len_new);
> > > 1724     		kunmap_atomic(src);
> > > 1725
> > > 1726     		if (ret) {
> > > vvv     CID 1527270:    (OVERRUN)
> > > vvv     Overrunning array "zram->comps" of 4 8-byte elements at element index 4 (byte offset 39) using index "prio" (which evaluates to 4).
> > 
> > Hmm... I don't really see how prio can evaluate to 4.
> 
> Yeah, I agree. This looks like a false positive. I'm not sure why
> Coverity triggered for it. Looking at the extended report, it seems to
> not have any idea that prio_max is correctly bounded.
> 
> Sorry for the noise!

No worries!